In the proposed research, the techniques of immuno-biology and computer technology are combined to develop a new method to distinguish infection, immunity, and Arthus reaction associated with Coccidioides immitis. Guinea pigs will be immunized with killed arthrospores, infected with live C. immitis, and sensitized to develop the Arthus reaction, with extra potent coccidioidin. Lymph node and buffy coat cells will be secured from each sensitized and control group, stained, and examined for their DNA distribution patterns. The DNA distribution patterns of Feulgen stained nuclei will be evaluated by a series of computer programs. This will result in the extraction of sets of image parameters related to the texture, or pattern of distribution of the stained material. These parameters, in their value and correlation, have been shown to be sensitive indicators of the physiologic state, and manner of response of cells.